Last month we learned that online music service Slacker would debut its own player sometime before the holidays. Today the company made it official with the announcement of their "Portable" portable music player. The device features a 4-inch screen, 15, 20 and 40 station capacities, the ability to play your existing MP3s and WMAs, 10 hours of battery time, and it will work with Slacker Basic Radio and Premium Radio services. The Portable is now available for pre-order at $199.99 (15 stations, 2GB), $249.99 (25 stations, 4GB ) and $299.99 (40 stations, 8GB) . Expect the device to ship on, or before December 13th, 2007. [Slacker via Gearlog]